In short, after shenanigans revolving around travel around dimensions a modern army( A Marine Expeditionary Force if you want to be precise) end up invading a world that is still in the 19th century. The modern army came with full supplies and gear, they also are carrying with them three small-range nuclear rockets.

There is no resupply coming for the Marines.

The defenders would be equivalent to the Grande Armée at it's best, plus any modifications or advancements needed to win.

The goal for the marines would be to hold until they could be rescued, while the goal of the natives is to destroy them. (The time frame is whatever the plot demands)

The conflict would have started after the Marines bombed a civilian center accidentally, the barrier of languages and customs meant the conflict quickly got out of control. Due to plot reasons the Marines will not be able to forge alliance with the locals.

My question is: What changes or advancements I would need to give the 19th century army to give them a fighting chance against their enemy?

Edit: The time frame is whatever is necessary to severely cripple or destroy the Marines, it could go for days, months or even years. I want the Grand Armee to win within that time -- which I think will be difficult -- so I'm asking what change is necessary to make them able to win. The terrain and local supplies will probably be the worst possible for the marines.

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    $\begingroup$ 'fighting chance': do you mean a single battle, a series of battles in of month or two, or a war in years? There are different answers $\endgroup$ – ADS Jun 23 '17 at 6:26
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    $\begingroup$ three small-range nuclear rockets might be counter productive in terms of fallout and radiation half-life limiting areas for advancement (or withdrawal...). Unless they are to be used as some sort of end stage cyanide pill ;-( $\endgroup$ – IlludiumPu36 Jun 23 '17 at 7:38
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    $\begingroup$ Can they resupply? If not you can just wait till they run out of ammo... If they can, it's game over for the 19th century world, unless the marines cannot replace its losses. $\endgroup$ – Rekesoft Jun 23 '17 at 7:45
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    $\begingroup$ Sounds like you invented Rome, sweet Rome and added gunpowder. This topic has been done to detah, yeears ago, on Reddit, and I doubt that changing it to the 19th century would make much difference $\endgroup$ – Mawg Jun 23 '17 at 9:14
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    $\begingroup$ What are the invading army's goals? Find and destroy a particular objective? Destroy the 19th century army? Destroy the 19th century country's industrial base? Occupy and rule? Until we know the military objective of the invasion, we can't really give an answer (even though several people have tried). $\endgroup$ – Grimm The Opiner Jun 23 '17 at 11:58

21 Answers 21


In short, time and lack of reinforcements and supply will win. I assume that the army's goal is to conquer a big country like US, Russia or Australia.

Non-combat losses

In 1930-1939 military theoreticians thought that an army of tanks could go indefinitely. But even before WWII it was clear that a couple of weeks on the march could lead to 50% losses. Modern technology is more reliable but the principle still holds (maybe with a smaller percentage). Torn tracks, broken engines, leaks in fuel pipes - you choose between 'brigade waiting while single tank is repaired' and 'giving up broken tank'. With thousands of various pieces of machinery, every hour something gets broken in a whole army.

Also with people. Driver gets ill (appendix or broken leg due to pretty nurse accident) and tank is abandoned on the roadside. You need a car to deliver him to medics. You need people who will care for him and... where is the safe place?

So the army needs logistical support which contains a hospital, repair shop, some police - in fact, another army.

Limited resources

In the 19th century there is no proper fuel, nobody could provide ammo and even powder is different. Modern tanks carry only several dozen shots which could be fired out in a hour. Also marines have no more than a dozen clips. Sure, an army has some stockpiles but they are also limited.

The trap of fall back

After some time, the army commander could decide to save the fuel only for important missions. But horses can't drive a heavy truck, not to mention a tank. Modern people also don't have the skill to ride. So the modern 'mechanized' army will fall back to a 'walking' one while the opponents still have a 'horsed' army.

Uselessness of nukes

The largest battle in 19th century involved nearly 600,000 soldiers on both sides. But there were many countries involved, and the biggest army from a single country was 160,000 which is only 2 times bigger than a modern army. With superiority in conventional weapons, a modern army doesn't really need to use nukes. A nuclear bomb is good to horrify enemies. But with fear, the desire to destroy a threat will come. Since it's a short-range rocket you can't destroy the capitals of all the big countries. Ergo, if you don't want to fight with the whole world, you don't use nukes.


There are examples mostly not about how to win superior enemy but about how difficult to conquer.

  1. Let's look at French invasion of Russia in 1812. Along with guerrilla tactics, the Russians had a big army, so Napoleon couldn't relax. He prepared supply but underestimated duration and distances. The huge army lost from non-war reasons 'more men than all the battles' - even though both sides were from the 19th century, so they could use enemy's ammo and didn't need rare fuel!
  2. When Europeans arrived in America, they won many battles and received supplies. They had a lot of people wishing to travel. But they could start only with fortresses and small colonies and it took decades to conquer the country.
  3. Less relevant is The War of the Worlds by H. G. Wells. The Martians were superior in technology and well-equipped for building factories, but they lost because they could not take into account all the details.
  4. Europeans in China. They had a superior army but lacked in logistics (travel to China took months). Also expeditionary forces were small relative to the population of China. They established their missions, forced the Chinese to accept some laws and just drained what they wanted. They didn't conquer the country and didn't even change the ruler.

IMO, the best thing the Marine Expeditionary Force could do is

  1. Capture the capital of a small country.
  2. Say you are the new ruler.
  3. Make peace with neighbouring countries and enjoy life in the 19th century.
  • $\begingroup$ The idea of them trying to capture the capital of a small country is interesting, specially with them being grinded down by te lifestyle of the time. $\endgroup$ – Sasha Jun 23 '17 at 10:24
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    $\begingroup$ In the mid 1800s we had developed processes to distill kerosene; many modern tanks use multi-fuel diesel engines that could be adapted to use kerosene. If the engineers are clever, they could implement fuel heating systems that conserve existing fuel supplies or use kerosene for startup/shutdown, and burn coal tar (which was reasonably common in the 19th century) as the primary fuel. $\endgroup$ – Doktor J Jun 23 '17 at 19:54
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    $\begingroup$ Stranded marines capture small capital. New marines arrive to rescue stranded marines. Stranded marines don't want to leave, fight new marines. New marines now stranded, take a capital of their own. Rinse, lather, repeat. How long before we realize they were ALL MARINES THE WHOLE TIME? $\endgroup$ – Lord Farquaad Jun 23 '17 at 20:25
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    $\begingroup$ @LordFarquaad it's Marines all the way down. $\endgroup$ – errantlinguist Jun 24 '17 at 17:24
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    $\begingroup$ @DoktorJ The problem is not ony to reproduce refining process but run it on a big volume. Also modern fuel has less contaminants than decade ago. Primitive process give you a prmitive fuel and for advanced one (not mention to modern) you have a lot of catalyst and other chemistry. Even wood is possible. But I can't take it seriously $\endgroup$ – ADS Jun 24 '17 at 20:01

A similar situation already happened. When Cortes conquered the Aztec empire, he only had a small group of technologically advanced troops, in most battles over 90% of his force was composed of native allies, who have chosen to rather be ruled by the Spanish than to become human sacrifices in Aztec rituals.

To be successful, your modern army should ally themselves as soon as possible with a local power. The locals will provide the supply of food and the population base (and anything else needed to run a country, from policing to tax collection), and also the bulk of the army, fighting the enemy as they used to, and the modern troops will provide the fist which punches through the enemy. Therefore the losses could be minimized for the time travelers, and they could split up their forces to fight at multiple locations without risk.

There is no other way if the time travelers intend to stay long (or indefinitely). Otherwise, every victory they win would be a Pyrrhic one, every man lost, and every single bullet fired would be an irreplaceable loss, while their enemies could replace any losses given enough time.

However, allying themselves with a local power, or taking a side in an already existing war, they could certainly tip the scales and could make anyone they choose to be the winner. From now on, careful diplomacy could dictate what share of the victory they would be entitled to. As they have the force to be able to destroy any army and level any town, nobody would dare to double-cross them.

  • $\begingroup$ They wouldn't be able to ally themselves with the natives due to outside interference to make sure the conflict happened. The entire situation was created to goad Modern Earth into basically a genocidal war against an weaker enemy. $\endgroup$ – Sasha Jun 23 '17 at 18:32
  • $\begingroup$ @Sasha If that's the case, you need to add that to the question. $\endgroup$ – Schwern Jun 24 '17 at 0:32
  • $\begingroup$ 1. The sum forces of Cortes, including ally Indians, were only a bit smaller that those of Aztecs. 2 Cortes was taken for a living God, because he fit in some their prophecy. So this example is a fallacy. 3. The question was how to struggle AGAINST modern invasion, not FOR them. $\endgroup$ – Gangnus Jun 25 '17 at 18:23

Guerilla Warfare

By this I mean that the 19th century force must give up its focus on a standup battle. Any attempt by such a force using the tactics of the time will result in its being slaughtered. Modern troops, dug in and with proper fields of fire and ammo supply can more or less hold off anything short of human wave attacks, and 19th century armies (of the European persuasion) didn't do that. Machine guns with interlocking fields of fire on flat ground are essentially impervious to infantry attacks - see, for instance, the First Battle of the Somme.

Instead, the defenders must disperse and stay dispersed. Hit and run, sniping, and night attacks are the ticket. By refusing to meet the invaders in battle, they never lose. Of course, they don't win, either, and such a contest becomes a battle of political will. This will be very difficult for the defenders to do, though. 19th century technology does not include radios, so communications among the dispersed units is slow and uncertain, and the invaders have an enormous advantage over any unit they can locate. Night attacks, also, are fraught with peril, since the invaders have night vision devices.

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    $\begingroup$ This isn't a good idea. 19th century armies were drilled for standup battles, modern armies know Guerilla warfare. This would be just playing into the hands of the modern army. It might make the army more survivable for a certain period of time, but a win would be out of the question. $\endgroup$ – Raditz_35 Jun 23 '17 at 8:55
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    $\begingroup$ The idea would not necessarily be for the 19th century army to adopt guerrilla warfare, but for the local population to rise up against the time-traveling invaders. After all, the very term guerrilla was popularized by the tactics of the Spanish against the invading French under Napoleon. $\endgroup$ – Stephan Kolassa Jun 23 '17 at 10:38
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    $\begingroup$ Asymmetrical warfare has given the USA a black eye since Vietnam. $\endgroup$ – Tony Ennis Jun 23 '17 at 11:50
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    $\begingroup$ A small force of highly trained professional soldiers adept at manouver, marksmanship, nightfighting, and camouflage, with modern explosives mines and claymores, are not gonna be out guerilla-ed by a 19th century army! $\endgroup$ – Grimm The Opiner Jun 23 '17 at 11:57
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    $\begingroup$ @GrimmTheOpiner - They don't have to be. Please reread my post. With the defenders hiding among the population, unless the invaders are quite remarkable politically they will not be able to root out the guerillas. Your position is characteristic of (most) Americans (I'm an American, by the way. Nam vet, 2 tours) in that you think that military action beats guerillas. It doesn't. (Incompetent) military action can lose, but it's not enough to win. $\endgroup$ – WhatRoughBeast Jun 23 '17 at 16:20

Victory can exist on many levels. Tactical, operational, strategical, political, ideological. If you have overcome on a higher level, losses on lower levels are not so important. For example, the great Russian field marshal Kutuzov was really fantastic on the operational/strategic level (political too, but nobody listened to him on that). In September 1812 Napoleon totally defeated the Russians. He won the large battle of Borodino. He took Moscow. But by a ruse movement (without battles!) Kutuzov won the war, first around Moscow and later the whole campaign in Russia. And he forbade his generals to fight! BTW, it was not his only win without a fight.

On the contrary, another famous Russian field marshal, Suvorov, was a genius tactician, but a very weak politician. He won all his battles against the Turks, often having 1/5 or 1/7 of their forces. But the behaviour of his army was such that the Turks hated him and would NEVER make peace with him. And he could not win the war as a result. The Turks simply refused to discuss matters. The Empress had to give that task to another field marshal, Repnin, who was not such an excellent tactician, but he was noble in his steps and the Turks had nothing against speaking to him. (This is from an old book from the 19th century - biographies of Russian marshals.)

Political winning is already described here. Even more powerful is winning ideologically - if the population gets info from trusted sources that the foreigners are disgusting - without honor, God-haters, satanists, or anything else - then even if they win all the battles, they still cannot exist in a surrounding area that totally hates them.

As for tactical/operational winning, it is possible, too. Only notice, that the modern army will win if the old army uses any tactics from the late 20th or early 21st centuries. On the contrary, some older tactics can work, because a modern army is not trained to fight against them. BTW, small-group tactics is much better known now, so a modern army is excellently prepared against it. Your heroes (read: you) should invent or find something unknown or well-forgotten or something that is considered impossible by modern men, either because of their neglect of their ancestors or different morals. Also, it could help to come up with steps that can be thought of by ancestors, but cannot be thought of by modern men.

So, if the solution is on a level other than tactics, it is easy - simply have a local general or a politician or a preacher much more talented than the modern ones. Here many solutions can be made. For example, officers can be bought - local states could offer to give them titles and positions of high importance... BTW, the older setting can be even more destructive in this direction - slaves, castles, grounds, power... Or if the modern general is stupid and arrogant and thinks that the locals should be his slaves - he has no chance at all.

As for the tactical solution, against night vision, radars, snipers, tanks, gas, hand grenades, mines, helicopters... you need a really genius and/or shocking move. For example, a kamikaze system could work. Of course, a genius move on higher levels would be even more useful and effective. Even more, it could move the whole civilization in a new direction of progress. That could be a great point of interest.

Edit. A contemporary army is highly inefficient in munition use. Hundreds of bullets have to be spent to kill one enemy soldier. So, under serious pressure, the modern army will be soon hapless, if it does not immediately create its own state and industry.

  • $\begingroup$ Welcome to WorldBuilding.SE Gangnus! If you have a moment please take the tour and visit the help center to learn more about the site. Have fun! $\endgroup$ – Secespitus Jun 23 '17 at 8:19
  • $\begingroup$ Thank you, DLosc, your edition is much better than my text. $\endgroup$ – Gangnus Jun 25 '17 at 18:20

Siege Conditions

If the modern people are confined to an area without fresh water, it becomes a waiting game.


The modern guys have no immunities to the local bugs. The locals have lived with that all their lives. Just like the Europeans killed the Native Americans via bringing diseases, the modern people will no longer have had those “old” diseases in their environment, and are in a similar position!

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    $\begingroup$ Offer them a glass of water. Let Montezuma's curse do the work for you. $\endgroup$ – L.Dutch Jun 23 '17 at 7:15
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    $\begingroup$ the modern people will no longer have had those “old” diseases in their environment, Modern people will mainly be the offspring of those who survived the old diseases, so it may lead to a degree of genetic immunity [e.g. sciencemag.org/news/2014/02/black-death-left-mark-human-genome ]. And of course, modern people are more knowledgeable about the causes of illness and how to properly sterilize water, disinfect wounds, etc. $\endgroup$ – SJuan76 Jun 23 '17 at 8:14
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    $\begingroup$ The spread of disease would also work in reverse. Modern flu strains could be pretty devastating back then, especially without modern hygiene. $\endgroup$ – Jason K Jun 23 '17 at 13:45

Which army ends up in which world matters here a great deal. According to the OP

(A Marine Expeditionary Force if you want to be precise) end up invading a world that is still in the 19th century.

Although MEF would bring their equipment, the 19th-century world not support their operations, significantly reducing the fighting power. They cannot bring, for example, the full GPS satellite constellation with them. Also, it is unlikely that the terrain of this world would be accurately triangulated with known fixed points. This would render most of MEF's navigation and localization equipment useless. Without accurate maps (and no satellites to quickly map it) navigation would be useless anyway. All this would prevent MEF use its artillery pieces effectively, limiting them to direct fire only.

Without electricity grid, MEF would be limited to diesel generators. Consequently, most of command and communication networks would be useless after the batteries drain for the first time. In combination with the above GPS issue, most planes wouldn't fly, or if they fly there is no way of directing them and their fire effectively.

Even with the limited capabilities, MEF would still have superior firepower. On the individual level; a modern soldier is trained to shoot-to-kill, and his marksmanship under fire would be superior. Also, even against a 1899-magazine-reloading-rifle, a modern assault rifle has superior firepower, let alone modern machine guns. On a more tactical level, and even with limited communications, a modern fighting unit would combine the firepower of all weapons assigned to it, and modern artillery and mortars would mow down the opposing old army pretty quickly. A modern tank, IFV or APC is almost completely impervious to all weapons a 1899 army fields.

The fact that MEF is not trained and optimized to fight the opponent would prefer the 19th-century army. The units would be smaller and thus destroying large amounts of enemy simultaneously difficult. Also, and especially early 19th-century, the opponent would be considerably less organized, so MEF would not find the kind of structures (command and control, resupply, logistics) that it is trained to find and eliminate. The enemy would also not emit any EM making the reconnaissance more difficult.

The limited environment of 1899 would limit the fighting power of MEF. Even then, the strategy of 1899 army is to reduce direct fighting to minimal. Instead, guerilla warfare against the already limited supply lines would be key.

With no way of replenishing, and mounting losses through sabotage and attacks, MEF would eventually run out of diesel and other fuels, grounding all planes, stopping all tanks and emptying all batteries for good. After this MEF would be communicating just as efficiently as the 1899 army, and without horses and with a lot of heavy equipment would become less mobile than the older opponent.

Now it is time for the 1899 army to strike. With superior maps and local knowledge, they should divide the MEF into smaller manageable pieces and attack them with superior force from all sides.

Conclusion: The older army should utilize its local knowledge of the terrain to stay away from fighting the superior force head-on. Instead, waiting, attrition and guerrilla warfare are used to drain the modern force from its key assets: fuel and electricity. This blinds and immobilizes the enemy, after which it is destroyed (small) piece-by-piece.

  • $\begingroup$ Really gets back to whether the MEF can be resupplied with replacement troops. If not, the opposing army would have vast recruitment potential and the ability to join forces with allied forces. $\endgroup$ – IlludiumPu36 Jun 23 '17 at 8:53
  • $\begingroup$ Indeed, and time frame matters too. Obviously, if (the story and) the 19th-century army can afford to wait out, they could let the MEF win by surrendering and wait a decade or two and win strategically. If there is to be one decisive battle and MEF still has most of their manpower and gizmos, the discrepancy in firepower is so big there probably isn't a way of attacking it with enough people simultaneously to win. $\endgroup$ – Tommi Sisso Jun 23 '17 at 10:49
  • $\begingroup$ If the MEF can run out of ammo and fuel, then they could be defeated by enough suicidal cave men. Doesn't sound like what the OP is asking because there is no need to introduce a Grand Armee. Once the initial slaughter is over, the cave men win. $\endgroup$ – Tony Ennis Jun 23 '17 at 11:58

It always seems to come back to one truism in warfare since time began. Battles can be won with superior equipment, but Wars are won with logistics.

That right there dooms the Marines over time. sort of.

It has been mentioned that things like GPS and such are going to be immediately useless. Electronic devices are only useful as long as the battery lasts. The most awesome machine gun, once it's out of ammo is just a metal stick. Even if they brought reloading stuff, 19th century gunpowder isn't going to be good for modern rifles, leading to jams, misfires, and other reliability issues. If they can't resupply, they can't fight for long. A protracted war and they won't win.

A much more important question is why would the continue fighting after they figure out that they have been time travelling. Who is the enemy, what is the mission? I would think that after the first battle, your Marines will shift focus from fighting to surviving and getting back to their own time.

Passive stuff like body armor and helmets will help your marines for a while. That's going to give them a chance to survive at least. If they stop fighting with the locals, or duck out to a neighboring country, their knowledge of tactics, discipline, and knowing what didn't work in future wars are going to make them some bad-a mercenaries.

There is likely at least one of the group will be familiar with resection and other map reading techniques, the rest can be taught. That will replace GPS, not as precise, but good enough. that's just an example. they may keep their modern rifles for sniping and long range work, at least until the Ammo runs out or goes bad, but will switch to the firearms of the time for everyday carry. Knowing how to shoot is going to make them marksmen among the everyday soldiers of the time. It won't take a huge amount of time, as I'm guessing you will have at least one who will have fired a modern muzzle-loader. Finally, your marines have already been trained in the use of bayonets and a variety of hand to hand weapons.

One thing that we may overlook is that Marines are very adaptable. They will probably adapt to the local conditions much more quickly than most would give them credit for. After all, they know very well that in combat, the plan never survives first contact with the enemy.

I would guess that once they become accustomed to their new surroundings, the marines would do OK. Semper Fi!

Now for the other side. First, leave the Marines alone. Spend some time talking and trying to figure out why they are there. Even a small group of Marines can cause horrendous damage to an opposing force. That is probably the best course. Marines are not dumb grunts.

If you are determined to fight the Marines, your best bet will be to try to pin them down. Make them run through as much ammo and supplies as you can as quickly as possible. Maybe pin the marines down, weaken and open a path to another position to pin the marines down, repeat as necessary. Wear them out and run them out of supplies. It will be horribly damaging to your country, and the loss of life will be horrible, but that's how you can beat them.

  • $\begingroup$ Depending what they pack, they should be able to keep thermal vision and radio running indefinately, by recharging them (solar panels perhaps?) for some years. $\endgroup$ – gmatht Jun 25 '17 at 16:18
  • $\begingroup$ @gmatht Maybe, but those are just toys in the overall scheme of things. The radios are not exactly going to be long range. The thing is, they are eventually going to fail one way or another. Even the best batteries die out after a few thousand cycles and there are no replacement parts. No resupply. I imagine the marines are going to realize this fairly quickly and start rationing their usage of anachronistic items $\endgroup$ – Paul TIKI Jun 26 '17 at 14:04

What changes or advancements I would need to give the 19th century army to give them a fighting chance against [a Marine Expeditionary Force]?

You need to give them a complete 21st century command structure, plus 21st century training... or at least post-WWII. They need 21st century C3I: Command, Control, Communications, Intelligence.

Nothing else will do. Dressing up a 19th century army with 21st century equipment and they're still a 19th century army with 19th century training, tactics, organization, logistics, and leadership. Giving them a few 21st century commanders will not do, they'll still be leading a 19th century Napoleonic army with a 19th century staff and officers and 19th century training and thinking.

Here's why.

30,000 Marines With Muskets Are Still 30,000 Marines

...and an unwieldy Napoleonic army with M16s is still an unwieldy Napoleonic army.

This is no contest. The pace and tactics of warfare have so changed and evolved so much since the Napoleonic Era that a 21st century army, even one 20 times smaller and equipped with Napoleonic equipment, would wipe the floor with a Napoleonic Era army.

The Marine's greatest weapon is not their fancy guns, but their mastery of C3I: Command, Control, Communications, Intelligence.


If you're going to send a military unit back in time to fight, an MEF is a good choice. They're fully self-contained, and lean: every one is a trained rifleman. An MEF features a Marine Division for ground combat, air wing, logistics group, an expeditionary brigade, and three Marine Expeditionary Units. The brigade and MEU also have their own ground, air, and logistics assets.

This means not only can they operate completely cut off, they're designed that way. This puts them in very good shape when they appear in the 19th century. This is what it means to be "expeditionary".

Technology Will Fail...

As others have noted, their technology will quickly break down once their supply of fuel and spares are gone. Maintenance units will be able to keep things together by stripping units for spare parts, and fabricate others; the lack of high quality steel and aluminum will make that very difficult. A small amount of diesel and jet fuel (which is basically kerosene) could be made on site, but not enough to fuel an MEF. Batteries can be recharged with the solar and wind generators they have on hand, but eventually the batteries will wear out.

Small arms will last longer, a well-maintained M16 will run forever, but ammunition will be a problem. While the brass cases can be reloaded, and bullets can be made, obtaining smokeless powder and primers will be a challenge considering they won't have been invented in the Napoleonic Era yet. Someone within the MEF will know enough chemical engineering to get that going, but it will be some time to get it set up, and more time to perfect their production to meet the tolerances of modern firearms. Still, they will be able to produce small arms cartridges that will safely fire, even if it might not cycle the action reliably. That is still an enormous advantage over a muzzle-loaded musket.

Point is, they have, perhaps, a few hundred hours of combat operations before their technology really falls apart. During that period they'd use their massive advantage to defeat the army in the field, acquire a base of operation, and capture sufficient supplies and weapons.

The only question is what to do with all the prisoners.

...But You Still Have 30,000 Well-Trained Marines

A 21st century MEF has so many non-technological advantages over a 19th century army it's not even a fair fight. It comes down to C3I: Command, Control, Communications, Intelligence.

In a 19th century army, the soldiers are poorly trained, and mutinous. Communications are very poor, but officers are not given independence. The result is an emphasis on drill, and remaining tightly packed for morale and control issues. Units are only capable of simple maneuvers. Battles happen during the day, in large open fields with good sight lines for the commanders so they can see what's going on and issue orders, and no obstructions to break up their formations.

This basic problem of command and control plagued military tacticians well into World War I and World War II. It's not until the introduction of Stormtrooper tactics late in WWI that we see something recognizable as large-scale modern military tactics.

In sharp contrast 21st century Marines are all highly trained, motivated riflemen. Even without 21st century equipment, their communications will be excellent. But more importantly tight control is not as needed allowing them to be flexible in ways a Napoleonic commander would consider utter chaos. Small unit commanders have the training, authority, and independence to accomplish their goal without constant command and control and can range far and wide across the battle-space wrecking havoc from all directions.

The 21st Century Pace Of War

The pace and scope of warfare has also changed. Napoleonic armies fight during the day at chosen battlefields. The rest of the time they're resting, marching, foraging, and training. The battle happens on the battlefield. In contrast, to a Marine, everywhere is the battlefield all the time.

While the large Napoleonic formations are still marching toward the battlefield in long columns, Marine platoons will be scouting and infiltrating around their flanks and rear. Before the army can even reach the battlefield and form up, they'll be constantly under hit-and-run attack from all sides. Napoleonic armies do not react well to being surrounded and constantly harassed, they'll be confused, hesitant, and demoralized.

The Marines will attack their camps at night. Snipe their leaders. Steal their artillery. Capture their very vulnerable and long supply trains leaving them without food and ammunition. Marines will move through and fight in forests and other bad terrain that break up Napoleonic formations. The Marines will never allow the enemy breathing room to maneuver into a set-piece, open field fight that Napoleonic armies are trained for.

The Marines will know all the weaknesses of a Napoleonic army and how to exploit them. In contrast, the Napoleonic commanders will have never seen anything like how the Marines fight; commanders for whom warfare has remained basically the same for the last few centuries will have to play 200 years of catch up through some of the most ferocious changes in military tactics while their men are dying.

There's no need to kill all 650,000 men of the Grande Armée, after a few weeks of this harassment by an enemy who will not stand and fight they'll desert in droves.

Simply put, a Napoleonic staff does not have the C3I to keep up with the pace of 21st century warfare. Their commanders, and their orders, will always be three steps behind the Marines.

Settle In For The Long Haul

The best course of action in this scenario is to continue to whittle away at the enemy, always avoiding an open field set-piece battle, while establishing a secure base of supply and operations to await rescue. "Liberate" a few towns and small cities, give them a decent government (even a 21st century military government will be better than a 19th century civilian one), and start reconstructing the 20th century (21st is too ambitious).

In the mid-run, they could make simple breech-loading, repeating rifles to give them a distinct firepower advantage. For example, something very simple like a Winchester Repeating Rifle would give them a devastating firepower advantage, even with black powder. With this they can fire a dozen accurate rounds in the time it takes a Napoleonic soldier to fire one poorly aimed shot.

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In the long run, the Marines could establish themselves as a technocratic mercenary kingdom. Their collective knowledge of science, engineering, and particularly metallurgy, will allow them to create technological wonders; just their ability to make high-quality steel would be enough. Their military training will make them highly desired to train other armies bringing in much needed hard currency. Their 21st century administrative and social expertise will allow them to govern and organize their territory more efficiently than any neighbor. Their reputation as fierce and bewildering warriors will keep their enemies at bay.

  • $\begingroup$ Two quibbles: 1) Your complaints about 19th century armies is a reason why Napoleon won ... Napoleon had quite good generals. 2) The "every one is a trained rifleman" will be disadvantaged if they run out of ammunition ... muskets won't be much better for them than they are for anyone else. $\endgroup$ – ChrisW Jun 24 '17 at 23:49
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    $\begingroup$ @ChrisW 1) Napoleon had good generals for the time, but not for the 21st century. He also had a large national army which could absorb casualties in a way others could not. Finally, the OP didn't say we're facing Napoleon, just that era; and in that era the leadership was appalling. 2) The point of the whole answer is even using contemporary weapons, a Marine's key advantage is 200 years of military science. A platoon of Marines armed with muskets is still a platoon of Marines and far, far more effective than a platoon of 19th century musketeers. $\endgroup$ – Schwern Jun 25 '17 at 0:00
  • $\begingroup$ Really interesting, I had been thinking in ways to counter their technology, but it seems the real danger is their training and philosophy. The idea of them settling in is interesting, but I can't use it, the most of the story will take place on modern Earth as the repercussions of this takes place. $\endgroup$ – Sasha Jun 25 '17 at 0:46
  • $\begingroup$ I'll definitely use the idea of Stormtroopers as part of their different timeline. $\endgroup$ – Sasha Jun 25 '17 at 0:47
  • $\begingroup$ Your style reminded me of Pratchett: But accidentally we have a thousand elephants following in the same direction! $\endgroup$ – Gangnus Nov 15 '17 at 12:37

Depends on when in the 19th century. Austerlitz? Balaclava? Mars-la-tour? Elandslaagte?

If the low-tech force has a magazine-loading rifle and reasonable numbers, the MEU is going to get seriously hurt. Same for the low-tech force, of course.

  • The MEU will have superior command and communications. That is somewhat countered by their small numbers.
  • Just how much supply will the MEU bring, and can they resupply? Can they tailor their gear? An AV-8 Harrier or F-35 Lightning is probably overkill, better bring a trainer-turned-COIN like the Pilatus PC-21. Few uses for the TOW, better bring extra mortars and MK19.
  • The equipment of the low-tech force would be somewhat inferior to the guerillas mentioned by WhatRoughBeast, countered by overall better organization, discipline, and numbers. Look at the estimates for Iraq, and compare with the size of the Germans in 1871.

Follow-Up: If the transfer of the MEU is an one-time event, their operations will grind to a halt in a week or so. Out of fuel, out of ammo, out of easily available food. If they immediately go to strict rationing and foraging, they might be able to postpone the inevitable, but they will only be able to operate for a few days, whenever they kick off.

  • $\begingroup$ They had no idea they would end up in this world, so they would have the regular equipment. The idea would be an world going trough their version of the Napoleonic Wars. $\endgroup$ – Sasha Jun 23 '17 at 10:15
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    $\begingroup$ @Sasha, see my edit. $\endgroup$ – o.m. Jun 23 '17 at 16:13
  • $\begingroup$ It seems my best bet would be to hit their supplies early on, make them fight a defensive battle with dwindling resources as the enemy sieges them. $\endgroup$ – Sasha Jun 23 '17 at 16:57

The defenders would be equivalent to the Grande Armée at it's best, plus any modifications or advancements needed to win.

Assuming the MEF is up against the Grande Armée, I guess the marines could decapitate the enemy forces (i.e. kill the officers), especially including Napoleon Bonaparte himself, with long-range rifle fire.

Napoleonic battles depend on morale and leadership (casualties aren't very heavy, battles end not when everyone is killed but when a leaderless rabble starts to run away).

IMO the MEF would do well with only their rifles and machine guns and tactics.

For the sake of simplicity, lets assume that:

  • We can ignore the marine's heavy artillery and airforce (let's assume they're unavailable due to lack of GPS, maps, runways, etc.)
  • Assume the marines have functional personal radios (or maybe not, who knows, maybe they have an encrypted radio which network depends on accurate atomic clocks or something; and/or the batteries run out, depending on the time scale)

So assume the marines are left with only rifles (M4) and light machine guns (M249 or M60) ... not to mention heavy machine guns and mortars and so on.

One of the things that might help the Grand Armee, a lot, is if the MEF were surprised without their ammunition being issued. I assume that's off the table though -- "the Marines bombed a civilian center accidentally" implies the Marines know they should be armed and ready for trouble.

So, otherwise I assume that:

  • The MEF has 20,000 troops
  • The Grand Armee has 600,000
  • Each MEF soldier carries 400 rounds of ammunition available on their person
  • There's ammunition for the SAWs and other machine guns

The MEF have an advantage compared to Napoleonic troops:

  • Napoleonic troops march in formation, do bayonet charges en masse, and fire musket volleys
  • Modern soldiers take cover (e.g. spread out and lie down, maybe entrench) and fire relatively accurate rifles (effective range of 500 metres)

20,000 marines times 400 rounds each implies 8,000,000 rounds total (even ignoring any machine guns). If 10% of those shots were effective, that would be a 100% casualty rate (of not only all the officers but all the men as well), just from the rifles, ignoring any heavier weapons.

So it's not looking good for the Grand Armee. In fact I'd guess they'd flee the field after only a 10% casualty rate, maybe especially if they lost their officers and NCOs.

To win they need some drastic change:

  • A long-drawn-out siege and/or scorched earth (win by starving the marines)
  • Fanaticism (willing to fight when officers are killed)
  • A change in tactics (e.g. nothing but irregular or less-regular troops, with rifles rather than muskets, more similar to American army in the War of Independence, or the voltigeurs)
  • Illness (dysentry?) or insanity (mutiny?) within the marine camp ... maybe the marines aren't immune to the local drinking water
  • Something (a moonless night, heavy fog) that negates the marine's advantage with ranged fire and turns it into a hand-to-hand melee at night (but wouldn't the marines have illumination mortar rounds, or something, to counter that?)
  • Smoke would help the Grand Armee. 19th century battles are smokey, not using smokeless powder, my impression is of units sometimes emerging through smoke at close range ... so a favourable wind and terrain, massed cannon fire, would make rifle fire less effective at long range (however I expect the automatic weapons fire would still be prohibitively lethal at short range)
  • A traitor, dare I mention that? If someone (or a whole faction) from the marine camp knew their tactics and technology and weaknesses, and defected (perhaps with technology) to advise the Grand Armee...

So a short-term battle looks one-sided. What about a long-term war though?

"An army marches on its stomach".

Part of the genius attributed to Napoleon was his ability to split his command, so that they'd march (and forage) along separate routes, and then bring those units together again in time for battle. If the time-frame is months or years then (depending on the terrain, climate, population) the MEF might have to disperse? Mingle with (acquire food from) the civilian population? And thus become an "occupying power" (which is different from and maybe more complicated then taking a "defensive position" in a firefight)? And so be vulnerable to insurgence tactics, line-of-supply and communication problems, medical and morale problems, and political problems ...


I think that people are significantly overstating the importance of GPS and other satellite-based systems in modern warfare. They are very useful in low-intensity conflicts but given the likely use of Anti-satellite weapons by any near-peer enemy all forces will have organic capabilities to replicate those reliant on satellites. A marine expeditionary unit has organic aviation capabilities which could reconnoitre and mark targets for artillery.

Unless your MEU is very foolhardy it would be very difficult for them to lose, as long as they conserve fuel and ammunition. A Napoleonic army would barely stand a chance against modern infantry (remember that musketry was considered at a decent level if they could fire 2 shots per minute in any weather - rapid fire in a modern army is thirty rounds per minute) let alone the likes of Harrier attack aircraft or the M1 tank.

The MEU also has the advantage of basing - they can sit offshore in their amphibious assault ship, which can easily defeat Napoleonic-era warships just using the 20mm anti-aircraft weapons; that's assuming that the Harriers and Cobras don't sink any attackers first.

If the rest of the World was happy to pool all of their resources and throw everything that they had - including taking tens of thousands of casualties - then they might just be able to win by sheer force of numbers; but I'm pretty sure they'd seek a truce.

  • $\begingroup$ Right, so my first move should be to ground them. Have their ships run ashore or maybe even damaged during the travel. Because of plot reasons the truce will be impossible at the this scene. $\endgroup$ – Sasha Jun 23 '17 at 16:39
  • $\begingroup$ It's a start, but there's still no answer to the air power of the MEU $\endgroup$ – Matt Bowyer Jun 23 '17 at 23:23
  • $\begingroup$ @MattBowyer: "conserve fuel and ammunition" and "air power" just cannot stay together for extended period of time. Do You have an idea of the amount of fuel needed for a single mission of one Harrier, Cobra or Apache? $\endgroup$ – ZioByte Jun 24 '17 at 12:40
  • $\begingroup$ A friend suggested blowing up a dam, they could still try to save some of the gear, but would have to leave a lot behind as they try to get away before the waters drown them. $\endgroup$ – Sasha Jun 24 '17 at 16:47
  • $\begingroup$ The OP is using an MEF. That's 3 MEUs, a Marine Division, air wing, etc... More like 30,000 soldiers. $\endgroup$ – Schwern Jun 24 '17 at 20:23

Don't underestimate 19th century weapons - the primary advances since then have been in rate of fire, not destructive capacity... your Marines wouldn't want to take advantage of that higher rate of fire, as it's unlikely they will find 5.56 and 7.62 ammunition in the 19th century. Further, the nitro based gunpowder of the 21st century didn't exist back then... it was largely black powder, which is dirty and will quickly foul the actions of modern firearms.

While still single shot, 19th century small arms could be most effective. The Whitworth rifle was put to very effective use as a sniper rifle during the US civil war - Union general Sedgwick was killed by Sgt E.R. Grace at a range of 800-1000 yards, using a Whitworth rifle.

Field artillery had also become very destructive by then, with cannon that had as long as a 12 mile effective range. Unless your Marines have weapons that can reach beyond that range, and enough ammunition to keep those weapons firing, the 19th century army can just sit back out of range of small arms, and pulverize your unit with artillery.

Motorized troops? Where are you going to get the fuel to keep those vehicles moving? Gasoline and diesel fuel weren't manufactured in any great quantity until the 20th century. It was coal and wood to produce steam back then.

Nukes? Sure, lighting one off might scare the armies away. But... how do they deliver those nukes? And can they keep doing it? They would have to fire one, and bluff the 19th century into thinking they had a lot more of them. Remember also that nukes have a limited lifespan, several years, before they have to be overhauled. Otherwise, the tritium used to boost the nuke will decay into 3He, helium that is missing a neutron and wants one, and that will kill a nuclear chain reaction by absorbing neutrons.

In short, your high tech MEF is going to run out of supplies fairly quickly, if they make full use of their firepower and mobility... with no hope of finding replacement ammunition that can function in those new weapons.

And, then what?

  • $\begingroup$ Contemporary nuclear weapons do not contain tritium; they use lithium-6 to generate it. $\endgroup$ – Loong Jun 24 '17 at 13:33
  • $\begingroup$ US civil war is late in the 19th century. I don't think Napoleonic artillery had a 12-mile range ... I think its cannon range was comparable to modern rifle range, maybe 500 to 1500 meters. $\endgroup$ – ChrisW Jun 24 '17 at 13:49
  • $\begingroup$ US civil war was 1861-1865. Large naval cannon could reach a range of 12 miles, hence the '12 mile' extension of of a country's sovereignty beyond it's shores into the ocean - that's as far as its shore based cannon could reach. During the US civil war, the most advanced field piece was the 3" Ordnance Rifle, with a range of about 2 miles/3.2km. $\endgroup$ – tj1000 Jun 24 '17 at 15:52
  • $\begingroup$ I think that was 3 miles, not 12, and that the large Napoleonic cannon (e.g. 24 pounder long) had a range of about 1 mile. I don't think they can win by firing cannon against the rifles ... assuming 30 cannon per 5000 troops, the 600000-man Grand Armee had three or four thousand cannon ... I don't think they prevail against the MEF's 20,0000 troops, especially assuming that nearly a quarter of those marines have crew-served heavy weapons (mortars and machine guns). $\endgroup$ – ChrisW Jun 24 '17 at 23:03
  • $\begingroup$ I think you underestimate the fighting power of an MEF! The M777 will happily outrange, outgun and outshoot any 19th century artillery. $\endgroup$ – Matt Bowyer Jul 30 '17 at 23:21

Like others that have answered previously , I concur that the Marines will be unchallenged on the battlefield at the beginning, but as time draws on, attrition and supplies shortage (logistics) will eventually win the day for the Grand Armee.

But do the Marines know that?
Are in any way expecting to have to last as long as possible?
What is their objective in that world?

Plotwise, it's very easy to setup a situation that, for example, their mission is:
'insertion - intense fighting for 48 hours (objective) - extraction'.
The MEF commander would have no qualms on reserving resources, instead would probably opt for spending them with abandon, in order to obtain the objective in the required dealine and minimize MEF casualties.

And then, extraction is delayed, and delayed, and delayed ... but it's too late for the Marines to save up resources now.

That's how they can easily lose a war that should be rightfully theirs!

  • $\begingroup$ oh! That's really clever! $\endgroup$ – Sasha Jun 25 '17 at 19:20

first give them the home cort advantage, that is to say have the fight go down on in the nineteenth centuries universe.

then give the nineteenth century a supreme advantage in numbers of troops

then let them some how sneak spies into the modern arms camp, I will leave the details on how up to you.

three have some small group of soldiers in the modern army mutiny, and join the other side.

the nukes are sabotaged or stolen.

do all these things and the nineteenth century might stand a chance might have a chance.

alternatively you could just give the nineteenth century superpowers.

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    $\begingroup$ The OP is using an MEF. That's 3 MEUs, a Marine Division, air wing, etc... More like 30,000 soldiers. $\endgroup$ – Schwern Jun 24 '17 at 20:23

Oh, Americans. Your answers are so detached from reality. This question has been answered not one, but several times in this century only. In short - Marines will lose.

All the weapons modern army have are meaningless when there's no will to use them. Without moral superiority modern army have no chance.

The conflict would have started after the Marines bombed a civilian center accidentally

So, Marines bombed civilian center and you somehow thinк that nobody will switch sides?! Although "Avatar" was science fiction, Manning and Snowden are real people.

There is no resupply coming for the Marines.

You seems to have no idea how quickly modern stuff fails. Germans panzer armies were destroyed by bad weather, when Russians were equipped by weapons from previous century.

they also are carrying with them three small-range nuclear rockets.

Tactical nukes are useless against sparse enemy. Unless you want to destroy a city (castle?). Such destruction will serve as motivation for local population to fight until the last man stands.

...But You Still Have 30,000 Well-Trained Marines

You never been in the army. Where did you got this strange idea that Marines are trained better then knights? Common "marine" is almost illiterate cannon fodder. Same as infantry in any century from the dawn of time. They we trained to use M16 and follow orders. Out of 30000 maybe only 1/10 can actually kill someone. Vast majority of modern army are support personal (mechanics, cooks, logistics etc). For contrary example, consider 20000 Chengiz-Khan army: experienced deadly warriors. Trained from the childhood.

What sets them apart is superior training and knowledge of history.

Average Marine have no knowledge of even his own history. Doubt he can even spell "knowledge of history". Already talked about "superior training".

In short, the Marines would have a few simple advantages and depending on how the capitalize on them, they could defeat a much larger forces.

In short, their will to fight will be broken, gear will fail, ammo will run short.

  • $\begingroup$ You really don't understand Marines all that well. First of all, the marines require the highest scores of all the branches of the US Military on the Standardized tests. These are not just dumb grunts. Further training on the history of warfare and such is a big part of boot camp. Your average marine is better educated on history than the bulk of college juniors. Marines are far, far from illiterate. I'll grant you that their training might not be up to snuff against the Kahn's, but that's about it $\endgroup$ – Paul TIKI Jul 26 '17 at 13:32
  • $\begingroup$ In addition, the marines have lots of nifty gear, but each and every one is trained to do without, or to use low tech alternatives. A map and a compass will get marines around without GPS. That's just an example. One of the most highly prized qualities among marines is creative problem solving. Will to fight? They will fight for each other, if nothing else. But they are also smart enough to know that without a clear mission, it's better to not fight until you have a reason to do so. Their leaders WILL ask "what is our purpose here" and be set to negotiate $\endgroup$ – Paul TIKI Jul 26 '17 at 13:40
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    $\begingroup$ Finally, you have an amazingly insulting comment born of supreme ignorance: 1/10 can actually kill someone?!?! Every Marine is a rifleman. period. Even if their day to day job is something else, every one of them is trained and able to kill. Moreover, in order to be a marine, they have to be able to do so at 500m with fixed sights. No scopes. $\endgroup$ – Paul TIKI Jul 26 '17 at 13:47

You asked how can the armies of the 19th-century compete with the MEU, but the real question is how long the MEU can survive before it is destroyed!

The devastating power of the MEU will initially cut through their opponents like an NFL tackle through a defensive line of five-year-olds. As they consume their fuel, ammunition and spare parts, they'll become less powerful and effective. In a short time, all advantages they had will be gone as their powerful war machines will quickly run out of fuel, their planes grounded, and futuristic weapons became totally useless without ammunition. Once this happens, the MEU is nothing more than a group of 2,000 soldiers with fancy clubs against a well-armed 19th-century army with vastly more men, more supplies, superior weapons, more bases of operation, and constant resupply.

However, if the goal of the MEU is to accomplish a specific task, such like topple the government of a country, destroy a city, or kill a prince or king, it could quickly and decisively accomplish that task without too much opposition. The indigenous army could not counter the MEU's superior weapons and tactics. Automatic weapons would destroy their order of battle. Their aircraft would destroy any artillery, destroy supply lines, and terrify the commanders as they sweep in raining death and destruction as they watch helplessly. The drones would provide the MEU commander an unsurpassed situational awareness, preventing any possibility of feints or surprise attacks. Armored vehicles, immune to the ball ammunition, break any defensive lines.


I think most have been said. Time does not favor the Marines here. They do in all likelihood not have the time or the materials available to build up a supporting industry to provide them with adapted fuel or ammunition. So they have about a week or so (From most estimates I've seen here) until they have to fall back on captured enemy weapons.

Granted, they can adapt them to work better than contemporary weapons, as Gwally noted, adding rifling and other modern know how. However, they have a limited amount of personnel and are working under pressure.

Also, one thing most other posters seem to have left out is that even a 19th century army and society would be aware of the usefulness of adaptability. And while the marines surely have their share of clever people and tinkerers to help them downscale to 19th century technology the opposing side would have more. They would also have spies. (Unless the marines can be guaranteed to keep their base of operations hermetically shut, not letting in supply traders and/or prostitutes, they will lose equipment to the enemy. An enemy who will now start dismantling the tech in order to figure out how to use it. Granted, they won't figure out radios or computers. But they'll get some leaps and bounds in ballistics and rate of fire.) Or even dissenters in their own ranks who will provide intel to the enemy for personal reasons (might be gain or might be unwillingness to partake in a slaughter... see the Rosenbergs for example).

So, if the conflict is longer than a couple of months (this provided the marines adapt weapons quickly enough to not just run out of weapons and ammo) the marines will be facing a completely new enemy. One with similar tactics and weaponry to their own (time adjusted) and with a infinitely larger production- and recruiting base.

Another thing: Once the marine artillery runs out of shells we'll get a rapid invention of trench warfare where the napoleonic army digs out all their old mortars, improves them and starts pounding on the marine base from the relative safety of holes in the ground. Sure... the reach wasn't great but they just have to be out of reach for whatever small arms fire the marines can muster. And the napoleonics can just keep building mortars. The marines probably won't even have the industrial base to melt down their useless tanks for scrap metal to start casting mortars of their own.

I'd drop my 21th century rags and set up shop somewhere where I hadn't made an enemy of the locals. Especially if I had useful skills that could be monetized. I think you'll find at least some of your marines will do the same.


The answer might be in the numbers...you have a limited size force having to potentially deal with countries that unite against a common foe...just like if aliens invaded Earth. Sooner or later the invading force will die off. So to answer your question, the art of diplomacy to get countries to combine forces.

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    $\begingroup$ Welcome to WorldBuilding.SE! If you have a moment please take the tour and visit the help center to learn more about the site. Have fun! $\endgroup$ – Secespitus Jun 23 '17 at 7:40

Reverse Engineering

After the first battle, the XIXers will try to get as much info on the weaponry as they can, and they will want to get their hands on a rifle. How they succeed is up to you. Then, the governments will stall for time until they can mass-produce a lesser copy of it.


I will reverse the question.

The only way the Marines can survive for extended periods of time is to chose a favorable land, fully occupy it and start XXI century industries, possibly using slave labor.

If they have the right kind of engineering competence they might be able to hold off the "Napoleonic Army" long enough to have some chance to start a whole modern industry, after which they will have stable logistics and thus a fighting chance.


This is not going to happen

I have read over the responses so far and some seem pretty accurate. The Marines will have an advantage at first, but while most of you think the Marines will fail with the loss of electricity and high tech, I think it will be just the opposite. The Marines suffer a loss from those weapons no longer working, but the Marines are going to kick some serious medieval butt with superiority in every other area.

The Marines have one aspect on their side few of you have really considered, training. I am not some oorah Marines kind-of-guy. I appreciate the esprit de corps, but there is one way the Marines can and will win, superior training over the forces of the day.

First off the bad news, many of their high-tech weapons will fail. They will have no GPS, electronic systems will fail, some of you are thinking they end up like the Colonial Marines in Aliens. What sets them apart is superior training and knowledge of history. Even if it’s a different history, military strategy has advanced over the years and this outfit will be trained in methods and strategies other armies have yet to consider. Modern military training is vastly superior to the 19th Century. Back then, an officer could become an officer because he was a nobleman or his family purchased the title. That doesn’t exist in a modern military unit. Armies in the 19th Century were nowhere near the highly trained modern forces of today.

19th Century soldiers could point and fire a musket in as little as 10 seconds, but Marines can learn the skills of older weapons and already know how to make enhancements. They know the dangers of smooth-bore cannons and understand that if they had them rifled, they could increase the firepower from the cannons 10-fold over smooth-bore and wipe out defenses.

Several of you pointed out that the diseases of the 19th Century would wipe out the Marines. For the most part, this is not correct. Of the diseases that still survive, they have evolved to be more formidable, not less. The Marines would be susceptible to smallpox, since most of them would not be immunized, but they already have the knowledge to self-vaccinate. A disease that could wipe out a regular army has less of a chance with the Marines. Add to that their training in basic hygiene gives them another leg up over regular conscripted troops.

And finally, fear is a huge advantage the modern Marines have with the inclusion of the nuclear warheads.

In World War II, when the fight in the Pacific had the US setting up to invade Japan itself, those Marines in the initial invasion would have been slaughtered. What we now know after the war ended is that the Japanese accurately predicted where we would invade. There's no doubt the US would have won the war, but the loss of life on both sides would have been staggering. The atomic bombs dropped on Hiroshima and Nagasaki brought the war to a swift close, removing the need for an invasion. So long as the fear of the advanced weapons exists, the Marines have the advantage in war. That fear could be enough to allow them to take a nation and train a larger force to help support them.

In short, the Marines would have a few simple advantages and depending on how the capitalize on them, they could defeat a much larger forces.

  • $\begingroup$ Good points, but I doubt they would be able to capture enough guns and ammo to equipe themselves, specially artillery pieces. Do they would even have the means to rifle the canons with their regular equipment? Marines would carry smallpox vaccines with them regularly? Those aren't conscripted troops, but a professional army. $\endgroup$ – Sasha Jun 23 '17 at 18:05
  • $\begingroup$ Nobody, short of a lab in Atlanta has a vaccine for smallpox. But similar viruses like cowpox can be administered and lessen the effects of smallpox. That's pretty common knowledge. One focused attack on an Armory gives the Marines all the weapons they need. The ability to shoot accurately was not a skill taught to people before the Civil War. Teaching skills such as marksmanship became an issue because out of 10 soldiers, only 1 was a decent rifleman. That lead to the foundation of the National Rifle Association in 1871. $\endgroup$ – gwally Jun 23 '17 at 18:41
  • $\begingroup$ Right, so they would need a decentralized Armory to prevent this kind of thing, or maybe just a general ready to sacrifice the Armory before letting the enemy grab it. $\endgroup$ – Sasha Jun 23 '17 at 20:46

protected by Tim B Jun 27 '17 at 15:57

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